My nano-sumo bot project is still going.
I've had a number of attempts at getting under the 1 cubic
inch size barrier. And it looks a lot closer now.
I just discovered some 402 sized SMD LED's from LUMEX. So I
did a Atmega8 (MLF formfactor) PCB using 402 sized parts on
it as well. It eeks out a little bit more space on the PCB.
I still have a 603 sized component PCB just in case.

Now if I can only find some small rechargable Lithium-ion
battery cells small enough to work.
using non-rechargable cells sort of sucks as they are very
expensive.
I see tantalizing pictures, but no one selling them yet.
Or at least selling in small quantities.